Distillation control



Feb. 25, 1941. J. B. cLAFFr-:Y

DISTILLATION CONTROL 2 Sheets-Sheet l Filed Feb. 24, 195e C UNDE NSER PRODUCT /4/ REFLUX AMPLIFIER OUTPUT INVN R Feb. 25, 1941. J. B. cLAFr-'EY QISTILLATION CONTROL Filed Feb. 24, 1958 2 Sheets-Sheet 2 IBV TO ATTORN EY Patented Feb. 25, lil-41 2,232,840

UNITED STATES PATENT OFFICE DISTILLATIGN CONTROL Joseph B. Clancy, Philadelphia, Pa., assignor to The United Gas Improvement Company, a corporation of Pennsylvania Application February 24, 1938, Serial No. 192,197 8 Claims. (Cl. 7202-72) This invention pertains generally to distillacolumn I0, and at I2, a condenser with reflux and tion and pertains particularly to distillation with product lines I3 and I4 respectively. high efiiciency of separation and high through- The apparatus so far particularly described put. may be conventional in character and may be of It has been found that the eiiiciency of separaany design or construction known in the art. 5 tion and throughput of fractionating columns in Likewise it may be operated in any desired mangeneral, and packed columns in particular, are ner or for any desired purpose. closely associated with conditions which cause In the operation of column I0 the pressure flooding of the columns in that highest eiiiciendrop from the bottom to the top, or in other cies with highest throughput are obtained just words between chambers I6 and I5, will vary with l() below the flooding point. the vapor velocity up through the column, in-

Flooding is caused by excessively high vapor creasing with increase in vapor velocity up to the velocities which tend to prevent the counterflooding point. When the flooding point is current flow of reiiux liquid thus causing reflux reached the pressure drop increases very sharpl liquid to build up in the column and ll its enly. tire space, hence the term flooding A result Vapor velocity is determined by the pressure of ooding is a sharp decrease in eiliciency and in still I I, which in turn is determined by the throughput and a sharp increase in pressure rate of vapor generation or, in other words, the

o drop through the column. heat input.

- Vapor velocities are a function of the rate of In accordance with this invention, I vary the vapor generation in the still pot, and it is by a heat input at still II with variation in pressure close control of the rate of vapor generation, drop, decreasing the heat input when the presthrough means responsive to the pressure drop, sure drop approaches a flooding value and inthatI am able to continuously operate throughout creasing the heat' input when it falls below 20 a distillation, whether batch or continuous, with this value.

highest efficiencies and throughputs. Thus the operation of the column is kept in Other features of the invention reside in the the neighborhood of incipient flooding without construction, arrangement and combination of actually going -nto a flooding state.

parts, and in the steps, combinations of steps, As a result maximum efficiencies and throughand sequences of steps, all of which, together puts are obtained. 3U with other features, will become more apparent to While the means for causing the heat input at persons skilled in the art as the specication still II to vary with the pressure drop may be of proceeds and upon reference to the drawings in any construction suitableAJ for the purposes, I

which: find it convenient to employ a U tube I1 partly 30 Figure l is an elevation, partly in section and iilled with mercury I8 and having one arm I9 partly diagrammatical, illustrating one form of connected to chamber I5 as illustrated at 20 the invention; and another arm 2l connected to chamber I6 Figure 2 is an elevation, shown broken and as illustrated at 22. partly diagrammatical, illustrating another form Arm I 9 is shown with a set-oil? portion 23 of the invention; through the wall of which extends internally 40 Figure 3 is an elevation, shown broken and threaded boss 24 which in turn accommodates an partly diagrammatical, illustrating a third form externally threaded adjustable element 25 havof the invention. ing an end 26 extending downwardly into arm p Referring now more particularly to Figure I9. 4') l at II) is shown a column which has been repre- End 26 is connected through boss 24 and wire 45 sented as being of the multi-tubular packed type. 27 t0 0n@ Side 0f a SOUICB 0f eleCtriCal energy 28, Tubular columns usually comprise a plurality of the other side of which is connected through tubes connected in parallel and packed with a wire 29 to one terminal of the input of an amplisuitable phase contacting medium, although Iier 30. The other input terminal of amplifier single tube packed columns are frequently used. 30 is connected through wire 3| to mercury I8 50 While the invention is particularly adapted to in U tube Il.

tubular packed columns, it is also applicable to The output of amplifier 30 is connected to a distillation columns in general including those of solenoid valve 32 in line 33, leading to heating the bubble cap type. element 34. Line 33 might carry steam. liquid At iI is conventionally represented a still for or gaseous fuel or other heating medium, heat- 55 ing element 34 being accordingly chosen and positioned with respect to still I I for the utilization of the selected heating medium.

Electrical heating means 1s regarded as an equivalent in which case line 33 is an electrical circuit, heating element 3l is of the electrical type or is electrically controlled such as an oil or tar burner, or solid fuel burner, or a blower, and valve 32 is an electrically operated switch, rheostat or the like. Y

When a fluid heating medium is employed it is convenient to provide a. by-pass 35 around valve 32, flow through said by-pass being controlled by a valve 36.

'Ihe operation of the form of the invention shown in Figure 1 is as follows:

The still, column and conventional appurtenances being in operation, the height at which the mercury I8 will stand in arm I9 will be determined by the difference in pressure between chambers I6 and I5, or in other words the drop in pressure from chamber I5 to chamber I5. This height will increase and decrease with increase and decrease in such pressure drop.

Element is so adjusted as to bring end 26 to a position in arm I9 such that it will be contacted by the rise of mercury in arm I9 when the pressure drop reflects flooding or incipient flooding conditions.

A circuit is thus closed through the input of amplifier causing current to flow through its output circuit to operate valve 32 to completely shut oil, or to decrease the iiow of or otherwise regulate, heating medium in line 33 as desired or found convenient or necessary.

'The heat input to still II is thus decreased, reducing vapor generation and in turn vapor velocity.

With restoration of a desired pressure drop the mercury in arm I9 will fall to break the circuit through the input of amplifier 30 whereupon its output circuit will be deenergized and valve 32 will again open.

Valve 32 is preferably of such capacity when fully open as to send more heating medium to heating element 34 than 1s normally required, a condition which would cause the column IU to flood except for the control mechanism herein provided. The repeated momentary closing. or partial closing (according to the type oi' valve chosen) of valve 32 cuts down the flow of heating medium to the exact amount necessary for most efficient operation. f

When by-pass 35 is employed valve 36 .is adjusted so that the flow of heating medium through the by-pass is slightly less than required for normal operation. In this case valve 32 controls the flow of the additional heating medium re quired. This arrangement has the ei'lcct ci preA venting large surges in flow of heating medium.

It will, of course, be under `tood that the con,

nections to the column might be reversed so that the mercury will descend in arm i9 with increase in pressure drop. In this case breaking ol' the circuit through the amplifier will close valve 32. Valve 32 in this case will be of a type that closes when not energized. 4

While I have particularly described an ein-- bodiment of my invention it is to be understood that this is not by way of limitation and that other forms are possible.

This is illustrated in Figure 2 wherein a modified U tube Ila is provided with set oil portions 23a and 23h in arms I9@ and 2In. respectively, the latter being connected to the upper and lower chambers of a column in the same manner as arms I9 and ZI of Figure l.

Adjustable elements 25a and 25h and appuntenances are in all respects similar to adjustable element 25 of Figure l.

Boss 24a, is connected to one terminal of the input of an amplifier 30a through a source of electrical energy indicated generally at 28a, the other terminal of the input being connected to mercury Ia through wire 3Ia.

Boss 2lb is connected to one terminal of the input of an amplifier 30o through a source of electrical energy indicated generally at 28h, the other terminal of the input being connected to mercury IBa through wire 3Ia.

The output of amplifier 30a is connected to operating coil 40 of solenoid valve 32a.

The output of amplifier 30D is connected to operating coil 4I of solenoid valve 32a.

The arrangement is such that valve 32a has an intermediate opening for the flow of heating medium when neither of its operating coils 40 and 4i is energized.

When the mercury in arm Isa rises, due to an excessive pressure drop, to contact end 25a. and

close a circuit through the input of amplifier 30u, coil 40 is energized and valve 32a closes either partially or completely (according to its design) to cut down the heat input into the still.

The result is a reduction in pressure drop.

As the desired pressure drop is restored the mercury in arm ISa will fall below end 25u to break the circuit and valve 32a will return to its intermediate position.

Should the pressure drop fall below the desired point, the mercury lu will rise in arm 2in', to contact terminal 26h and close a circuit through. the input of amplier 3D1). This will energize coil 4I to open valve 32a beyond its normal setting, permitting an increase in flow of heating medium. This will increase the heat input into the still. i

The result is an increase in pressure drop.

As the desired pressure drop is restored the mercury in arm 2Ia will iall below end 25h to break the circuit and valve 32a will return to its intermediate position.

By a careful adjustment of adjustable elements 25a and 25h the pressure drop may be held be tween more or less definitely defined limits.

By-pass 35u, with valve 35u may be provided il desired.

Other modifications are possible without dew parting from the broad concept of the invention.

This is illustrated in Figure 23 wherein valve 'u 32D in line 33h, which conducts heating medium.

'is opened and closed mechanically instead olf electrically. Y

Briefly, the arrangement sln'iwn in Figure 3 comprises disc 5B, axi ly mounted so as to be rotatable about its center lil. A member 572 .tired to disc 5D extends beyond the periphery thereof and is connected through link 53 to lever 54 lul crunied at 55 and pivotally connected at 56 to control member 5'! of valve 32h.

Cmitrol nieniber 5l is of the type that opens and closes valveilli with upward and downvurr motion respectively, although any other type ci valve or regulating mechanism might be substituted, the necessary mechanical changes being well within the skill ol" persons skilled in the nrt.

lvlormtcd on the foce of disc 5D is a tube 5B bent monl or less in n, V and arranged so ihut one arm 59 is more or less Vertical and the other arm El) slopes upwardly.

nifi

ull

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accesso Arm 59 is connected through a rieiiiblc element 6l which may be a rubber tube, to line 22h which leads to chamber l5 oi Figure l.

Likewise arm 60 is connected through a iexible element 62, which may be a rubber tube, to line 20D which leads to chamber l5 of Figure l.

Tube 58 contains a liquid such as mercury illustrated at 63.

An adjustable device, comprising internally threaded member 65 fixed to disc titi and externally threaded member 66 having a Weight 6l at its end, and threadedly engagingr member $5 is arranged on disc l opposite member 5t and functions as a counterbalance.

The operation of the device shown in Figure 3 is as follows:

It Will be understood that mercury 63 ascends and descends in arm with increase and deu crease in pressure drop through the column across which tube 58 is connected.

When disc 50 rotates clockwise, as the result of mercury rising in arm G0, valve closes (para tially or totally according to design) to decrease the :dow of heating medium.

When disc 5D rotates counter-clockwise, as the result of mercury descending in arno tu, valve 3th opens to increase the flow of heating medium.

By screwing' member GG in and out of inemu ber Weight ill is adjusted radially with respect to axis 5|. Thus the device shown in Figure 3 may be adjusted to trip at any desired pressure drop to operate valve llt will be understood that may be of any diameter so that any desired volume and thus weight of mercury may be caused to ascend and descend in arm Ell as required to operate valve 32h and associated mechanism.

It is, of course, to be understood that the presn sure drop through any part of the column may be employed in place of the drop through the entire column if desired.

Furthermore, it will be seen that by adjustn ment of element 25, or elements 2do and 25o, or element 66, as the case may be, it is possible to employ my invention to operate columns with any desired pressure drop other than the preferred pressure drop more particularly referred to herein.

Having set forth and. particularly described several embodiments or my invention, it is to be understood that this is by Way oi' illustration, and that changes, omissions, additions, substin tutions, and/or modifications 2night loe made within the scope of the claims, Without depart ing from the spirit of the invention which is intended to be limited only as required by the prior art.

l claim:

l. Apparatus for the fractionation of iiuid mixture containing components of different volatilities, comprising a column for the counteru current contact of ascending vapor 'with descending liquid phase, means for generating said vapor phase, and means connected to said column at vertically spaced points and actuated by diierence in pressure between said points for controlling said rst mentioned means.

2. Apparatus for the fractionation ci' a fluid mixture containing components ot' different vol atilities, comprising a column for the coiniterm current contact of ascending vapor phase with descending liquid phase, a. still for said column, heating means for said still, and means conn nected to said column at vertically spe. ed points pressure between and actuated by difference said :tor controllir in a manner to deer e e input into still with loeren. respectively said difference in ersure 3. Apparatus for ,fractionation mixture containing components oi volatilities, comprising. column having phase contacting section ior the connterwui. contact of ascending 'vapor ing liquid phase, means ior vapor' phase, means actuated by pressure connected to colli :i spaced points, said points "n tion of said contact-, f tween, and means for controlling sa tioned means through said second inentio" means to decrease and increase the rate t. phase generation by said first mentioned with increase and decrease respectively differential pressure.

4i. apparatus :for the :fractionation of a mixture containing coinprn'w volatilities, comprising` a coloni current contact of ascend f descending liquid phase, said vapor phase, and ence in pressure between vertically spa in said column tor controlling tioned means to maintain the rate vapor generation loelov. that which would ine.

5. Apparatus for the fra/iti mixture cont 'iig componi d.. volatilities, comprising a nini l-tuhular for the countermciirrent Contact of vapor phase with descending liquic still for said column, l'ieedini,T means i still, and means actuated by difieren. e Y sure between vertically points in column for controlling said heating d. Apparatus for the :fraction y. mixture containing component volatlllties comprising a column 'Y current contact of ascending v descending liquid a stili said vapor phase, heating means and means actuated lay di'merence ii between vertically spaced l for controlling,y said heating1 mear the generation oi said vapor pidas the rate oi generation of vapor plies-e ately below that which. would cause no' line '2. iin a process for the fractionation c c mixture containing components r with volatillties wherein ascending vapor 55 counterecurrently contacted.

liquid phase in phase con ci utilising di erence in g tically spaced points along s path to control the rate ci vapor phase,

d. lin process for the :nurture containing coM volatilities wherein counter-currently conte l, i liquid phase in a phase conducting of utilising diii'erence in tically spaced points along path. to control the 'vapor phase to ina-i generation near inc aient nous crease the rate of vapor no ss:- said rate is suicient to e i 

